Section 2: Classifying Chemical Reactions

Chapter 6: Chemical Reactions

Learning Goals

Classify chemical reactions.

Synthesis Reactions

A synthesis reaction is a reaction in which two or more substances react to produce a single product.

When two elements react, the reaction is always a synthesis reaction.

Synthesis Reactions

Two compounds can also react to create one compound in a synthesis reaction.

Synthesis Reactions

All synthesis reactions follow this general equation: A + B AB

Decomposition ReactionsA decomposition reaction is one in which a single compound breaks down into two or more elements or new compounds.

Decomposition ReactionsDecomposition reactions often require an energy source, such as heat, light, or electricity, to occur.

Decomposition reactions follow this general equation: AB A + B

Single Displacement Reactions

In a single-displacement reaction, one element displaces another in a compound.

Single Displacement Reactions

Usually a metal will replace another metal, or a halogen will replace another halogen in single displacement reactions

Single displacement reactions follow this general equation: A + BC AC + B

Double Displacement Reactions

Double displacement reactions occur when ions exchange between two compounds.

Double Displacement Reactions

Double Displacement Reactions

Double displacement reactions will always produce either a precipitate, water, or a gas.

A double-displacement reaction follows the general form AB + CD AD + BC

Practice

Classify the following reactions: Na2O(s) + H2O(l) ⟶ 2 NaOH(aq)

Ba(NO3)2(aq) + K2SO4(aq) ⟶BaSO4(s) + 2 KNO3(aq)

Practice

2 Al(s) + Fe2O3(s) ⟶ Al2O3(s) + 2 Fe(l)

2 H2O2(aq) ⟶ 2 H2O(l) + O2(g)

Solid calcium reacts with chlorine gas to produce solid calcium chloride.

Practice

Write a balanced chemical equation for each synthesis reaction: Ag(s) + Br2(g)

Mg(s) + Cl2(g)

Practice

Write a balanced chemical equation for each decomposition reaction: Al2O3(s)

H2O(l)